Submersible liquid level transmitters are used in a variety of industries and applications. For example, it is often necessary to know liquid levels in cooling towers, water storage tanks, sewer systems, dam reservoirs, rivers, lakes, sewer treatment plants, accumulation pools, water towers, sand filter ponds in sewage treatment plants, sewer lift stations (which incorporate a well to serve as a storage buffer for sanitary as well as storm sewage), etc. In such situations, a sensor is lowered into the liquid being monitored. The sensor is typically coupled by a length of cable to a processor. The processor is often a programmable controller or a dedicated controller that takes the reading from the sensor (e.g. a PT-500 sensor could measure water level) and from other inputs, switches, sensors, selectors, etc. Based on the data received, the processor determines (according to its programming) what outputs (such as a pump motor) to turn on and the duration of operation. The processor will likely have alarm conditions set, such as water level being too high, or the pump operating for too long, and send messages when those alarm conditions are met, such alarms notify operators that human intervention is required.
Examples of suitable processors include, but are not limited to, Lift Plus pump lift station control panel manufactured by Wastech Controls & Engineering, Inc. (Chatsworth, Calif.); Total Control Unit (T2000-AD) pump controller manufactured by Open Control Solutions (Melbourne, Fla.); and pump control systems manufactured by Quality Manufacturing Company (Roanoke, Va.).
The submersible sensors typically have a very thin membrane or diaphragm on their bottom end, that is the primary sensory component in detecting liquid levels. However, as can be appreciated, the sensors are often placed in extreme and often harsh conditions. For example, there may be significant turbulence in the liquid being monitored. Additionally, solid levels inside the containers being monitored can interfere with the sensors. Therefore, cages are often employed to shield the sensors from conditions and materials that would either damage the membranes or interfere with their sensory capabilities.
Current cage and sensor assemblies are not totally effective at solving the problems identified above. For example, the components—i.e. the sensor component and the cage component—do not always have the same lifespan. For example, in some instances, the cage will become defective, but the sensor remains functional. More often, the sensors cease working, while the cages are in perfect working order. In either case, it is extremely inefficient, and wasteful and expensive to replace the entire assembly whenever a single component wears out.
This and other problems found in the prior art are solved by the present invention.